Three different types of operating tables are typically used in hospitals, namely stationary operating tables, movable operating tables and mobile operating tables. Stationary operating tables have an operating table column permanently fixed to the floor of an operating room and normally do not comprise an operating table base, and energy is supplied to them via fixedly installed cables. Movable operating tables have an operating table base which is connected to the operating table column and may comprise rollers, and a patient support surface which can be detached from and re-attached to the operating table column.
Operating table bases of mobile operating tables include rollers for moving the operating table so that they can be moved without auxiliary means and are suited for transporting a patient. During the surgical intervention on the patient, on the other hand, a safe stand of the operating table has to be guaranteed. In the case of simple operating tables this is accomplished by locking several transport rollers, while in the case of high-quality operating tables a chassis of the operating table base is lowered so that it rests on the floor. For this, the transport rollers are integrated in the operating table base adjustably in vertical direction and can be moved downward such that the contact of the chassis with the floor is interrupted and the operating table stands on the transport rollers.
Further, with mobile operating tables, the patient support surface usually is fixedly coupled to the operating table column and is not separated from the operating table column in hospital practice. Further, electric traction drives, preferably including soft start and safety brake function can be used, in order to move the mobile operating table by means of the electric traction drive. Stationary operating tables as well as movable operating tables and mobile operating tables may employ components which can be adjusted by means of an electric motor, such as an operating table column which is length adjustable by means of an electric motor for height variation of a patient support surface arranged on the operating table column, an operating table column head which is adjustable about two orthogonal axes for variation of tilt and swing of the patient support surface connected to the operating table column head, and/or components of the patient support surface that can be adjusted by means of an electric motor.
Mobile operating table bases with four integrated transport rollers are known, which have a hydraulic cylinder for each transport roller as well as a common control valve for the vertical adjustment of the respective transport roller. One disadvantage resulting from the use of the hydraulic cylinders is the relatively large vertical space and the relatively high costs. However, for reasons of accessibility, a flat structure of the operating table base is desirable. If the movement of the operating table is to be assisted by means of an electromotive traction drive, a further hydraulic cylinder and a further control valve are required for lowering the traction drive to the floor and for lifting the traction drive from the floor.